The sense of smell is closely related to the importance of taste and, surprisingly, plays a significant role in determining the flavors we detect when we eat or drink something. Wine connoisseurs are accustomed to smelling the wine before taking a sip. When evaluating coffee in general and specialty coffee in particular, aroma and flavor are among the two most important attributes. “Scent” is the factor that guides us into the sensory world of coffee before it begins to define various properties such as strength, fullness, aftertaste, balance, acidity… Relax with your coffee and join us to learn more about “The conversion of a fresh coffee aroma”.
Where does the aroma of coffee come from?
The distinctive aroma of coffee that we are familiar with is primarily formed during the roasting process. Although green and roasted coffee beans can have similar odor groups (such as aldehyde, pyrazine, or furan groups), roasting produces volatile compounds that provide a distinct, familiar aroma. In their research, Flament, Toci, and Boldrin discovered more than 1,000 volatile compounds in roasted coffee. They are classified into several groups, including furans (150), pyrazines (100), phenols and ketones (90), pyrroles (80), hydrocarbons (76), carboxylic acids (60), esters (55), alcohols (50), and aldehydes (50). (45). These compounds play the most crucial role in creating and assisting the human nose in detecting the aroma of coffee. Not all 1,000 volatile compounds are aromatically related. Only about 5% of these compounds, or about 50 odor compounds in coffee, can be responsible for the aroma of coffee.
Chemical compound exploration
The reactions that produce coffee aroma are classified into seven major groups:
- Maillard or non-enzymatic browning reaction between nitrogen-containing substances, amino acids, proteins, trigonelline, serotonin, carbohydrates, hydroxy-acids, and phenols.
- Strecker degradation.
- Degradation of individual amino acids, particularly sulfur amino acids, hydroxy amino acids, and proline.
- Degradation of trigonelline.
- Degradation of sugar.
- Degradation of phenolic acids, particularly the quinic acid moiety.
- Minor lipid degradation.
Finally, the combination of compounds formed after the above reactions cannot be ignored, which is the core factor that makes up the diversity of coffee flavors after roasting.
How we perceive coffee aromas
Two distinct mechanisms are involved in the perception of coffee aroma. To begin, we perceive the scent of coffee directly through the nose. Second, as we all know, the ear, nose, and throat are inextricably linked, so when we drink coffee, the aroma is also diffused into the nasal cavity receptors.
That is why, during the Cupping process, we must evaluate both aspects in order to score Aroma characteristics. “Dry aroma” (scent of dry coffee) and “Wet aroma” (smell of coffee when mixed with boiling water).
The number of aromas in coffee
Green beans do not have a distinct aroma; most of them have a grassy aroma, possibly with a slight fermentable aroma. Meanwhile, roasted coffee will have a more complex and varied aroma. As a result, the scent we’re discussing is unmistakably that of roasted coffee. Even if you delved deeper into the nuances of coffee aromas as a cupper, you probably couldn’t name the chemical compounds listed above. Instead, we can divide coffee’s “fragrance” into three major sensory groups: enzymatic, sugar browning, and dry distillation.
Fruity Aroma – Enzymatic
Because the coffee we roast, grind, and the brew is the seed of a fruit, it is only natural that the source retains some of the same fruity qualities as the vegetable origin. Its Enzymatic properties are the natural fruity and herbal aromas that we detect in coffee.
Some coffees have more prominent enzyme properties than others, which can be attributed to species characteristics, how it is grown and processed, the degree of roasting, and the ratio of preparation. According to analysts, many Latin American coffees have sweet fruity aromas, whereas coffees from East Africa, such as Ethiopia, Tanzania, or Kenya, have a dominant “sour” aroma. They are produced from natural acids.
Brown Sugar Aroma
The variety of carbohydrate components and nitrogenous compounds found in coffee beans provide the basis for two “super classic” roasting reactions: the Maillard and Caramel reactions. Sugar Browning’s distinctive odor is due to the numerous product combinations formed by reactions between “sugars” and amino acids and sugar autolysis. The aroma emitted by this process in coffee beans will be similar to toast, chocolate, barley, malt, or simply “burnt sugar.”
Dry Distillation – Just a “pungent” Aroma
Back to the structure of the coffee fruit: remembering that the majority of the design of the seed cells is cellulose (also known as fiber), most of this “woody substance” is also burned and transformed into more minor odor compounds during the roasting process. Because we do not digest cellulose, the breakdown products are not pleasant; this group is represented by the way they smell spicy, savory, smoky, and woody. However, instead of immediately associating the smell with “burnt” or something, try associating it with more pleasurable experiences such as the aroma of resin, cloves, black pepper, and so on.
Importance of fresh coffee to aromas
It’s not as if the older the wine, the better it is. Coffee that has been aged for an extended period will affect its taste and its aroma. Manufacturers and roasters advise their customers to use roasted coffee within two weeks of purchase. Coffee beans begin to lose flavor and aroma after roasting. The scent has almost vanished after a month, affecting the quality of the brewed coffee. If you want the best aroma, purchase roasted coffee directly from a local brand. Most specialty coffee roasters roast to order, which means that your coffee will not be roasted until you place your order. When your coffee arrives, it will have been roasted within the last week and will be at its best.
Another option for trying many different types of coffee grown in various countries worldwide is to learn how to roast coffee at home. After learning about roasting, the final step is to select a reputable, high-quality green coffee brand from the coffee-growing region of your choice.
What is Coffee Aroma?
PERFECT DAILY GRIND(2019). What Creates Coffee Aroma? Understanding The Chemistry
HaiVan(2021). Khoa học cảm quan về mùi hương cà phê